Various kinds of single point mooring systems are known, for example from U.S. patent specification Nos. 3,187,355; 3,515,182; 3,908,212 and 3,913,157.
The loading and unloading operation of a ship moored to a single point mooring system is carried out by means of liquid transfer through a flow line extending between liquid supply facilities and the ship. In order to allow movements of the moored ship during these operations, the flow line section extending between the single point mooring system and the ship usually consists of a comparatively fragile flexible conduit.
Although the process of liquid transfer through single point mooring system has been developed to a high level of reliability, it incidentally may happen that damage is inflicted to the flow line because of the occurrence of an excessively high liquid pressure in the flow line. Said occurrence may for instance, be caused by a pressure surge initiated by a rapid closure of a valve in the flow line during the liquid transfer process. Minor damages of the flow line may reduce the service period of the flow line considerably. A major damage of the flow line may even cause a rupture of the flow line during the liquid transfer process, which may lead to environmental pollution. Furthermore, repair of a part of the flow line which is not readily accessible may require smooth weather conditions and an extensive repair operation causing a long down-time of the system.